Long lines to vote in Arapahoe County that left some waiting as long as four hours drew concern from Democratic state leaders late Tuesday.

Gov. John Hickenlooper and Sen. Michael Bennet visited Centrepoint Plaza in Aurora and found voters standing, waiting to vote.

"I met one who waited three hours, and some said they waited 3½ and four hours," Hickenlooper said. "That's too long. People have jobs, and they've got to get back to work."

He said part of the problem seemed to stem from the fact that voters flocked to a few high-profile vote centers, ignoring other centers where there was little traffic. He said the Romney and Obama campaigns might have inadvertently caused the problem by directing voters to a select few vote centers.

A pair of mail boxes at the corner of 12th Avenue and Lafayette Stret in the Capitol Hill neighborhood of Denver on Tuesday were tagged with an Election Day theme. More Colorado election photos. (Karl Gehring, The Denver Post)

"So many people came to a small number of vote centers that they were a little bit overwhelmed," Hickenlooper said. "Most people stayed in line, and most were in a good mood. It was inspiring. People were just joyful to exercise their right to vote."

Nancy Doty, Arapahoe's clerk and recorder, said she responded by sending elections workers to Centrepoint, armed with iPads, to try to divert those waiting in line to other polling places where long lines did not exist.

"Some voters took advantage of that, and some voters opted to stay in line and wait," Doty said.

She said four additional voting machines were added to Centrepoint during the day, and four additional elections judges were sent there to help the check-in process. By 9 p.m., the lines had been cleared, she said.

Colorado House Speaker Frank McNulty, R-Highlands Ranch, said that although long lines faced voters in Arapahoe County, he was not worried. Doty, a Republican, can handle it, he said.

There were scattered reports of long lines at other polling places in the state, but Arapahoe County appeared to have the longest wait times.

In addition to long lines, tempers flared in some places as voters waited to cast their ballots earlier Tuesday.

At Mission Viejo Library in Aurora, a man who identified himself as conservative was shoving his camera into the faces of those waiting in line for up to an hour and taking their photographs, said former Colorado Gov. Roy Romer.

Romer said he admonished the man to leave voters alone and to stop harassing them.

"People are struggling to have their right to vote, and we just can't have people intimidated," Romer said.

Earlier in the evening, county clerks reported that thousands of Colorado mail ballots had been rejected because of signature issues. Voters either didn't sign the ballot or election officials determined there was a discrepancy.

County clerks said the numbers were in line with what they were expecting, but, should there be a razor-thin race, verifying these ballots will become much more pertinent.

Those with rejected ballots will be notified and then have eight days to respond and verify their signatures. Those left without responses will be given to the district attorney for investigation of possible fraud, said Larimer County Clerk and Recorder Scott Doyle.